Electrode feeding device for electric arc apparatus



Sept. 19, 1939. s. 3 ANDERSON 2,173,149

ELECTRODE FEEDING DEVICE FOR ELECTRIC ARC APPARATUS Filed Dec. 28, 1925'? 2 Sheets-Sheet 1 INVENTOR GEORGE \J. AND/5250M BY ATTORNEY P 19, 1939- G. .1. ANDERSON 2,173,149

ELECTRODE FEEDING DEVICE FOR ELECTRIC ARC APPARATUS /lmnnm\\ l 157 3 1 13s /4/ 2% ga INVENTOR GEOQGE J. ANDEQSON ATTORNEY Patented Sept. 19, 1939 UNITED STATES PATENT OFFICE ELECTRODE FEEDING DEVICE FOR ELECTRIC ARC APPARATUS Application December 28, 1937, Serial No. 182,053

16 Claims.

This invention relates to electric arc apparatus and has particular reference to a device for feeding an electrode of an arc lamp.

In arc lamps operated by direct current the major portion of the illumination is derived from a concave crater formed at the tip of the positive electrode or carbon by the are extending across the tips of the positive and negative electrodes. This crater is therefore positioned at the point where the illumination created thereby can be best utilized, 1. e. the focal point of the optical system for the arc lamp.

To insure an unflickering and uniform illumination throughout the cross sectional area of the beam projected by the arc lamp, the crater at the tip of the positive electrode must remain symmetrical and no uneven voltage drop should occur across the tips of the positive and negative electrodes to change the intensity of the light produced thereby.

To permit the whole image of the tip or crater of the positive electrode to be projected by the optical system of the lamp, the negative electrode is generally arranged at an angle to the positive electrode. This requires constant rotation of the positive electrode about its axis to prevent the crater from burning into an unsymmetrical shape and thus projecting an unsymmetrical image. It has been discovered that the best speed of rotation of the positive electrode is dependent upon factors which are different than those factors which determine the longitudinal feed of that electrode to compensate for burning away of the tip thereof.

In cases Where a constant voltage is available and where the carbons used all have the same burning rate, the feeding and rotating speeds of the electrodes may be predetermined and the feeding apparatus built accordingly. However, in instances where the voltage supply is not constant, or where carbons of different burning rates are successively employed, it is desirable to regulate the various electrode feeds in accordance with such varying conditions in order to obtain a maximum efficiency of operation. For example, if the voltage of the current supplied to the electrodes is reduced, the electrodes should be fed at a slower speed and vice versa. The motion picture industry is a notable example of a place Where such above noted varying conditions exist. In photographing sets or scenes, large numbers of arc lamps are employed, many of which may be turned off and on at difierent times, thus greatly changing the load conditions of the current supply and consequently-effecting a change in the voltage. The above conditions are especially noticeable in cases where portable generating equipment of relatively small capacity is employed, for example for motion picture production on location or emergency purposes.

One object of this invention is to change the rate of longitudinal feed of an electrode independently of the rate of rotation thereof.

Another object is to change the rate of feed of an electrode while in operation.

Another object is to impart a plurality of feeding impulses to an electrode during each rotation thereof.

Another object is to readily interchange different electrode feeding units in an electric arc apu paratus.

Another object is to provide an electrode feeding unit of simple construction and ready accessibility of the parts thereof.

The manner in which the above and other objects of the invention are accomplished will be apparent from the following specification read in conjunction with the accompanying drawings wherein:

Fig. 1 is an elevational view of an electric arc apparatus embodying the present invention,

Fig. 2 is a sectional view partly broken away of the drive shaft assembly for the positive electrode head.

Fig. 3 is a view showing the forward portion of a positive electrode, partly in section.

Fig. 4 is a longitudinal sectional view through the positive electrode head.

Fig. 5 is a transverse sectional View of the positive electrode head and is taken along the line 55 of Fig. 4.

Fig. 6 is a. transverse sectional view of the positive electrode head and is taken along the line 66 of Fig. 4.

Fig. '7 is a front view of the spiral gear member Fig. 8 is a fragmentary sectional view showing the drive for the electrode carrier and is taken along the line,8-8 of Fig. 4.

Fig. 9 is a transverse sectionalview through the electrode gripper gears and is taken along the line'99 of Fig. 1.

Referring particularly to Fig. 3 it will be noted that the tip of a positive electrode I0 is formed into a concave crater l I. To effect the maximum efiiciency of illumination, it is necessary that the crater ll be symmetrical and of a definite shape in cross section dependentupon the amount of current and voltage'used as well as the type of electrode. The shape and symmetry of the crater 16 by means of insulating material 2|.

are generally governed by the rotation and longitudinal feed of the positive electrode, thus necessitating accurate control of such rotation and longitudinal feed. Usually, both positive and negative electrodes are formed of comminuted carbon bound with a suitable cement.

Referring to Fig. l, the entire arc apparatus is supported upon a horizontal base 12 which is adapted to be secured at the bottom of a suitable arc lamp housing (not shown) with the crater I l of electrode l9 situated adjacent the focal point of the optical system of the lamp. A positive head generally indicated at 13 for supporting and feeding the positive electrode l0, and a negative head generally indicated at [4, for supporting and feeding a negative electrode l 5, are both supported from base l2 by a standard It suitably secured to the upper surface of base l2. Head i3 is electrically insulated from the standard it by a layer of insulating material ll. A contact ing brush I8 is provided to insure a frictional electrical contact with the positive electrode IQ and is supported from the standard l5 through a bracket 25 suitably insulated from the standard A bus bar 22 electrically connects the brush member l8, through bracket 28, to one end of the coil of an electro-magnet 23 suitably secured to the under surface of the base l2. An insulating bushing 22' is provided in base l2 to permit bus bar 22 to pass through the base !2 without contacting the same. A second bus bar 24 connects the opposite end of the coil of electro-magnet 23 to a terminal 25 secured to and insulated from the under surface of base l2.

The negative head i4 is supported on one end of a lever 25 which is pivotally mounted at ill on the standard 15 to permit movement of the negative electrode l5 toward and away from the positive electrode lil for the purpose of striking an arc therebetween. Head i4 comprises a base 28 having a downwardly projecting stud member 29 thereon received and adjustably secured within a socket 38 provided at the end of lever 25. A U-shaped bracket 3! is suitably secured on the base 23 and has bearings therein at either end thereof to rotatably support a worm shaft 32 having a pair of oppositely inclined worms 33 and 34 formed thereon. A worm gear 35, meshing with the worm 33, is rotatably mounted on the end of alever 35 pivotally supported at 3? on the bracket 3|. Gear 35 has a cylindrical gripper portion indicated by the dotted lines 38 formed on one side thereof to engage the upper surface of the electrode IS. A second worm gear 45, meshing with the worm 34, is rotatably carried at one end of a second lever 4 i, pivotally mounted at 42 on the bracket 3|. Gear 49 also has a cylindrical gripper portion 43 adapted to engage the under surface of the electrode i5. A compression spring 44 is provided between the opposite ends of the levers 36 and 4! to urge the gripper portions 38 and 43 of the worms 35 and 48, respectively, toward each other and thus secure frictional contact with the electrode 15. A contact brush 45 engaging the forward end of the electrode I5 is hinged at 46 and 47 to the under surface of the base 28 and is urged against the electrode [5 by a spring (not shown) to form an electrical contact. A flexible metallic strap .48 insures an electrical connection between the brush 45 and the lever 26. The standard l6 and base l2, both of metal, form the remainder of an electric circuit between the electrode 95 and asecondterminalEll, which is provided. on the under surface of base 12 adjacent the terminal 25. From the above it will be seen that the electrodes ill and i5 and the electro-rnagnet 23 are provided in series between the terminals 25 and 56. The lever 25 is urged in a clockwise direction so as to contact the tip of electrode l5 with the tip of electrode It for striking purposes by means of a compression spring 5| interposed between the lever 26 and a bracket 52 extending from the standard it. The rearwardly extending end of the lever 26 is pivotally secured at to a link 54 which, in turn, is pivotally secured at 55 to a second link 56. Link 56 is pivotally supported at 51 by a bracket 58 depending from the under surface of the base 52. An armature 52 provided on the link 55 intermediate the ends thereof is adapted to be drawn into contact with the core 23' of electro-magnet 23 when current is passed through the coil of this electro-magnet to cause the negative head [4 and linkage connected therewith to assume the position illustrated in Fig. 1. In this position the tips of the electrodes H] and i5 are separated a predetermined amount to support an electric are therebetween.

A single electric; motor 5i, suitably secured to the under surface of the base i2, is provided to drive the feeding mechanisms of both the mega tive head l4 and positive head IS. The connection between the worm shaft 32, forming the driving element of the feeding means on negative head l4, and the motor 6! comprises in series a universal joint 52 coupled to worm shaft 32, an intermediate shaft 53 connected at one end thereof to joint 62 and at the other end thereof to a slip coupling 64, and a second universal joint 65 connecting the coupling 64 to a drive shaft 66 journaled within a bearing fill formed in the base l2. A ratchet mechanism (not shown) of conventional construction is provided in a suitable housing 58, secured to the under surface of base 12, to transmit an intermittent movement to the intermediate shaft 63. This ratchet mechanism derives its rotation from a gear boX generally indicated at 59, the gears (not shown) of which are driven by motor iii.

The mechanism of the positive head l3 which will be described hereinafter is also driven by the motor 6i through gear box a shaft "0, a second gear box '5 I, the gears of which are not shown, and a drive shaft assembly 72. A rheostat (not shown) may be provided in the motor circuit of motor 6! to vary the speed thereof and thus vary the various feeds of the negative and positive electrodes. However, such a variation in speed will effect a proportionate variation in the feed and rotation of the positive electrode if] as well as in the feed of the negative electrode l5.

As shown in Fig. 2 the drive shaft assembly 12 is formed into two shaft sections '13 and 14 coupled together by means of a slip coupling 75. The lower end of section 14 is coupled to a gear shaft 15 extending upwardly from the gear box H by means of a readily removable coupling 11. Coupling 11 comprises a head 18 secured to shaft 16 and having a longitudinally extending slot formed therein in which extends a transverse pin 8| provided on the lower end of the shaft section 14.

The slip coupling 15 comprises a sleeve 16 secured to the lower end of the shaft section 13 by a pin 82 and has a longitudinally extending slot 83 formed therein in which is guided a transverse, pin il l provided on the upper end of the shaft section 14. A compression spring intermediate the adjacent ends of the shaft sections I3 and I4 urges these sections apart to resiliently retain the lower end of section I4 coupled to the gear shaft 16. The upper shaft section I3 is coupled to the driving mechanism of the positive head I 3, to be described hereinafter, by means of a universal joint 86. Joint 86 is electrically insulated from the shaft section I3 by means of an insuated coupling 81.

Referring to Figs. 4 to 8, inclusive, I shall now describe the mechanism of the positive head I3. Head I3 comprises a cylindrical housing 88 having an apertured end wall 89 at the forward end thereof and being open at the rear end thereof. A base is integrally formed on the lower part of housing 88 for the purpose of supporting the head I3 on the standard I6 (Fig. 1). An electrode receiving aperture 9I is provided in the end wall 89, centrally thereof, to permit the positive electrode I0 to be fed therethrough. A cylindrical heat shield 92 of an asbestos or ceramic material having an electrode receiving aperture 92' therein aligned with that of 9| is secured to the end wall 89 of housing 88 by screws 93. Shield 92 acts to prevent the interior of the head I3 from becoming unduly heated by the are formed across the tips of the positive and negative electrodes. A cylindrical casing 94 open at the end thereof adjacent the open end of housing 88 is fitted over a portion of the outer circumference of housing 88 and is removably secured thereto by screws and 96 (Fig. 6). Housing 88 and casing 94 form a substantially enclosed compartment to house the electrode feeding and rotating mechanism. A bearing counterbore 91 is provided at the rear of the casing 94 and coaxially therewith to receive a ball bearing assembly 98. A cap 99 having a centrally located electrode receiving aperture I00 therein is secured to the end of casing 94 by screws 99 to retain the ball bearing assembly 98 in the counterbore 91 and prevent longitudinal movement thereof. An electrode carrier generally indicated at IOI is rotatably supported by the bearing 98. Carrier IOI comprises a tubular member I02 having a longitudinally extending passage I03 formed therein to loosely receive the electrode I0. Member I02 is mounted in the bore of the inner race 98' of ball bearing 98 and is secured therein by a lock nut I04 screw threaded on the end of member I02. A crown gear member I05 is provided on the member I02 and is held in driving relation therewith by the clamping action of lock nut Referring to Figs. 4 and 5, it will be noted that the forward portion of the member I02 is formed into an enlarged head I06 having a longitudinal slot I0! extending therethrough. A pair of diametrically opposed, transversely extending, grooves I08 and I09 are formed in the head I06 to receive a pair of stud shafts H0 and III, respectively. Gripper gears H2 and II 3 situated in the slot I01 are rotatably journaled on the shafts -I I0 and II I, respectively. Tension springs H4 and H5 are provided between the ends of the shafts H0 and III to resiliently urge the teeth of the gears H2 and H3 into engagement with the positive electrode I0. A spiral gear member 6 is rotatably journalled upon a bearing portion II'I formed on the member I02 directly behind the head I06. Gear H6 has a set of spiral gear teeth I2I on one face thereof, which teeth mesh with the teeth of the gripper gears H2 and H3, and are adapted to rotate the gears H2 and H3 about their respective axes on relative rotation of the tubular member I02 and the gear HE. A plurality of serrations or detents I22 are spaced around the periphery of gear I20.

A three lobed cam I23 is secured by screws [24 to the face of crown gear I05 adjacent the gear II6. A cam follower I26, movably supported by the casing 94, has a ball bearing I21 mounted in the lower end thereof which bearing is adapted to ride on the surface of cam I23 to intermittently raise the cam follower in a vertical direction. Follower I26 is slidable vertically in a guide I28 secured to the upper surface of casing 94 by screws I29. A compression spring I30 provided in a well I3I formed in the guide I28 urges the cam follower I28 downward at all times. A stop screw l32 is screw threaded vertically within the follower I25 and has a conical point I33 therein adapted to engage any one of the serrations I22 of gear member II6 when the ball I21 of the cam follower I26 rides upon a flattened portion I34 of the cam I23. Screw I32 extends to the exterior of the head I3 and has a knob 535 thereon whereby it may be adjusted vertically by an operator from the exterior of the head I3 and while the apparatus is in operation. A look nut I36 is provided to lock the screw I32 in any desired position.

Crown gear I05 is meshed with a pinion I31 carried on a stub shaft I38. Shaft I38 is journalled within a bearing bushing I39 carried by a boss I40 which is secured to the under surface of the casing 94 by screws MI. The shaft I38 of pinion I3? is suitably secured to the universal joint 86 (Fig. 1).

In operation, the positive electrode I 0 is inserted through the aperture I00 in cap 99 of head I3, thence through the bore I03 of member I02, and thence between the gripper gears H2 and I I3. Since gears I I2 and I I3 are resiliently urged toward each other by the tension springs l I4 and H5 these gears will be merely spread apart by insertion of the electrode I0 therebetween and will frictionally engage diametrically opposed portions thereof. Thereafter the electrode I0 is moved past the brush I8 and in frictional contact therewith.

The negative electrode I5 is inserted in the rear of the negative head I4. By pressing the levers 36 and M together at a point adjacent the spring 44 the gripper portions 38 and 93 of the worm gears 35 and 40, respectively, will be moved outwardly permitting the electrode I5 to be passed therebetween. The electrode I5 is thence moved past the contact brush E5 in frictional contact therewith.

The tips of the electrodes l9 and I5 are adjusted in correct relation with each other, these tips being in contact with each other before current is passed thereacross. When current is applied across the terminals 25 and 59 the closed circuit caused by the tips of electrodes I0 and i5 contacting each other will permit the electromagnet 23 to be actuated to effect a counterclockwise movement of the lever 23 against the action of the spring 5I, this movement being limited by the engagement of the armature 60 on link 56 with the core 23' of the electro-magnet 23. Due to the path of the volatilized carbon particles extending between the now separated tips of electrodes I5 and I5, the current will continue to pass thereacross forming an are.

On operation of the electric motor BI, which is preferably started simultaneously with the striking of an are between the electrodes I and I5, the worm shaft 32 will be intermittently r0- tated to feed the electrode I5, through the worm gears 35 and 7.6 and their respective gripper portions 38 and 43. Rotation of motor 6| will also cause the crown gear I in positive head I3 to rotate continuously, thus effecting rotation of the positive electrode II] by virtue of the frictional engagement therewith of the bodily moved gripper gears H2 and H3 carried by the tubular member I02. When the cam follower I28 engages a lobe of cam I23 the stop screw I32 will be raised out of engagement with one of the serrations I22 formed on the gear member IIE. Thus gear member H6 will be permitted to rotate with the member I92 resulting in a cessation of the longitudinal feed of the electrode l9. However, as one of the flattened portions I34 of cam 23 rides under cam follower I26 the stop screw I32 will be lowered into engagement with one of the serrations I22 of gear H6 thus holding this gear in fixed relation with the casing 94. As the tubular member Hi2 continues to rotate while the gear H6 is locked against rotation by the screw M2 the relative movement between spiral gear H6 and the member I32 will cause the gripper gears H2 and IIS to be rotated about their respective axes while being rotated as a whole about the axis of the electrode ill to impart a longitudinal feeding movement to this electrode. This feeding movement will continue until the cam follower I26 is again raised by a successive lobe on cam I23. By adjustably raising or lowering screw I32 the interval of time during which the conical point I33 of screw I32 is engaged with one of the serrations I22 on gear member H6 may be regulated, thus regulating the amount of each feeding impulse. That is, if the stop screw I32 is adjustably lowered relative to the cam follower I26 the conical point 533 thereof will engage one of the serrations I22 at an earlier moment on the downward travel of cam follower I26 and will be disengaged from that serration at a later moment, thus holding the gear member H6 in a fixed position for a longer period of time and effecting a greater longitudinal feed of electrode Ill while a flattened portion I34 of cam I23 passes under the cam follower I26. It will be noted that adjustment of screw I32 effects regulation of the longitudinal feeding movement of the electrode Ii! independently of the rate of rotation thereof about its axis. Since each feeding impulse is of considerable duration and since there are a plurality of impulses for each revolution of the electrode II], it will be noted that the slight unevenness of longitudinal feeding movement imparted to the electrode ID will be insufficient to cause a flicker or change in illumination of the arc.

Screw I32 may be adjustably lowered to such a point in the cam follower I26 that the conical point I33 thereof will remain in engagement with a serration of the gear III-l during an entire rotation of the cam I23. In this event a continuous longitudinal feed may be imparted to the electrode II).

In lieu of the three lobed cam I24 imparting three longitudinal feeding impulses to the electrode II! for each rotation of the electrode carrier IN, a cam having any number of lobes may be substituted therefor to give any number of longitudinal feeding impulses for each revolution of carrier It'll. Furthermore gears similar to that of H6 but having serrations of a different pitch may be substituted to permit a finer or coarser control of the length of each longitudinal feeding impulse.

I In the event that the positive head I3 is to be repaired or cleaned or that a similar unit is substituted therefor, the casing 94 carrying thereon the rotatable electrode holder IOI may be readily detached from the housing 88 by removal of the two screws 95 and 96 (Fig. 6). The casing 94 may then be slipped out of engagement with the housing 85 and the lower end of the drive shaft I2 carrying the transversely extending pin BI (Fig. 21) may be slipped out of the coupling member "I8. This feature is especially valuable in are lamps used in the motion picture industry where delays caused by replacement of feeding units in arc lamps are considerably expensive.

Although the invention has been described as being embodied in a feeding unit for a positive electrode, and although it is particularly applicable thereto, it is to be understood that the invention may also be applied to the feeding unit of a negative electrode as well.

I claim:

1. An electrode feeding device for electric arc apparatus comprising an electrode carrier, means for rotatably supporting said carrier, means comprising a gear on said carrier for longitudinally feeding an electrode, a cam on said carrier, a cam follower for said cam, means for movably supporting said cam follower, a screw holder actuated by said cam follower, and a screw adjustably mounted in said screw holder for intermittently engaging said gear to control the operation of said feeding means.

2. An electrode feeding device for electric arc apparatus comprising a casing having a wall, an electrode carrier rotatably supported by said casing, means for rotating said carrier, said carrier having an electrode receiving passage therein coaxial with the axis of rotation thereof, a member supported by said carrier for relative independent rotation about an axis co-axial with the axis of rotation of said carrier, said member being normally rotatable with said carrier, means operatively connected to said member and said carrier and on relative rotation of said carrier and said member imparting a feeding movement to an electrode in said passage, a cam operatively connected to said carrier, a reciprocating cam follower engaging the working surface of said cam, means on said casing for supporting said cam follower, a stop member extending through said wall and carried by said cam follower and adapted to engage the periphery of said first mentioned member to interrupt rotation thereof, said stop member being adjustable from the exterior of said casing and in the direction of reciprocation of said cam follower to vary the length of time said stop member is in engagement with said first mentioned member.

3. An electrode feeding device for electric arc apparatus comprising a housing, a casing removably attached to said housing, said housing and casing forming an enclosure, an electrode carrier rotatably supported by said casing and extending into said enclosure, said housing, casing, and carrier having co-extensive apertures therein to receive an electrode, a cam on said carrier, means on said carrier for feeding an electrode through said apertures, and means movably supported by said casing and adapted to be actuated by said cam for controlling said first mentioned means.-

4. An electrode feeding device for electric arc apparatus comprising a housing having an electrode aperture, a casing attached to said housing and having an aligned electrode aperture, means for attaching said casing to said housing, an electrode carrier, means for rotatably supporting said carrier in said casing, means on said carrier for feeding an electrode longitudinally, means carried by said casing for rotating said carrier, a drive shaft for said last mentioned means and a removable coupling for said drive shaft. 1

5. An electrode feeding device for electric arc apparatus comprising a housing having an elec trode aperture, means for supporting said housing in a fixed position, a casing, means for removably attaching said casing to said housing to form a compartment, said casing having an electrode aperture therein aligned with said first mentioned aperture, electrode feeding means for feeding an electrode through said apertures, means in said casing for supporting said feeding means in said compartment, a gear in said casing operatively connected to said feeding means, a second gear rotatably supported by said casing and meshing with said first mentioned gear, driving means for said second gear, and a removable coupling intermediate said driving means and said second gear, whereby said casing and said electrode feeding means may be readily detached from said housing and said driving means 6. An electrode feeding device for arc apparatus comprising a cylindrical housing having an open and a substantially closed end, a cylindrical casing having an open and a substantially closed end, the open end of said casing fitting the open end of said housing to form a compartment, means for removably securing said casing to said housing, the closed ends of said housing and easing having aligned electrode apertures therein, an electrode carrier rotatably supported in the aperture of said casing and extending into said compartment, said carrier having a passage therein aligned with said apertures to receive an electrode therein, means carried by said casing for rotating said carrier, means carried by said carrier and said casing adapted to feed said electrode through said apertures and passage on rotation of said carrier, a drive shaft for said first mentioned means and a removable coupling for said drive shaft.

7. An electrode feeding device for are apparatus comprising a cylindrical housing, means for supporting said housing, said housing having an apertured wall at one end and being open at the other end, a casing having an apertured wall at one end and being open at the other end, means for removably securing the open end of said casing to the open end of said housing to form a compartment, said casing having a bearing bore in the apertured wall thereof, an electrode carrier, bearing means in said bore for rotatably supporting a carrier in said compartment, said carrier and the apertured end wall of said housing having aligned passages therein to receive an electrode, means on said carrier and actuated by said carrier for feeding an electrode through said passages, a gear on said carrier, a second gear meshing with said first mentioned gear, means in said casing for supporting said second gear for rotation about an axis normal to the axis of said first mentioned gear, means for driving said second gear, and a removable coupling intermediate said second gear and said driving means.

8. In an electrode feeding device for electric arc apparatus, the combination comprising a casing, a driving member rotatably supported in said casing, a cam connected to said driving member, a driven member mounted in said casing for rotation about an axis co-axial with the axis of rotation of said driving member, means normally forming a driving connection between said driving and driven members, feeding means operatively connected to said driven member for feeding an electrode, a cam follower in engagement with the working surface of said cam, a guide member having a sliding bearing surface for supporting said cam follower for reciprocation, and a stop screw threaded in said cam follower and adapted to engage said driven member to interrupt the rotation thereof when said cam follower is reciprocated.

9. Electrode feeding mechanism comprising the combination of a casing having a bearing at one end thereof, an electrode tube in said bearing, a feed gear and a cam mounted side by side in said casing on said tube at the same side of said bearing, a guide member on said casing opposite said gear and said cam, a follower for said cam in said guide member, and means on said follower for stopping said gear in certain positions of said cam.

10. Electrode feeding means according to claim 9 wherein said stopping means comprises an adjustable member, and a hand operating device therefor accessible at the exterior of said casing.

11. In an electrode feeding device for electric arc apparatus, the combination of a casing, means for feeding an electrode comprising a carrier and gripper wheels mounted thereon, a feed gear on said carrier for operating said gripper wheels, a bearing for rotatably supporting said carrier in said casing at one side of said bearing, a cam in said casing adjacent said feed gear and at the same side of said bearing as said feed gear, means for rotating said cam about an axis coaxial with the axis of rotation of said feed gear, means comprising said carrier normally forming a driving engagement between said feed gear and said cam; a cam follower engageable with the working surface of said cam, and a stop member operated by said cam follower and adapted to engage said feed gear to interrupt the rotation of said feed gear at certain times.

12. Electrode feeding mechanism for are apparatus comprising the combination of casing having a closed end, an open end, and a circumferential side wall, a housing having a closed end and an open end, aligned electrode apertures in the closed ends of said casing and housing, the open ends of said casing and housing being fitted together to form a compartment, a bearing in the closed end of said casing, an electrode tube rotatably mounted in said bearing and extending into the open end of said casing, a drive gear having a cam thereon mounted on said extended end of said electrode tube, a scroll gear having a serrated circumference mounted on the extended end of said electrode tube closely adjacent to said cam, an aperture in the side wall of said casing, a guide member mounted in said aperture, a cam follower for said cam mounted in said guide member, and a stop screw carried by said cam follower and having an inner end cooperating with the serrations of said scroll gear and having an outer end accessible from the exterior of said casing for adjusting the electrode feed.

13. An electrode feeding device for electric arc apparatus comprising an electrode carrier, means for rotatably supporting said carrier, means comprising a spiral gear, having serrations thereon. on said carrier for longitudinally feeding an electrode, a cam on said carrier, said cam having a lobe with an extended Working surface, a cam follower for said cam, means for movably supporting said cam follower, a screw holder actuated by said cam follower and a screw adjustably mounted in said screw holder for intermittently engaging said serrations to control the operation of said feeding means.

14. An electrode feeding device comprising the combination of an electrode carrier, a casing over said carrier having a substantially closed end, a bearing in said closed end for rotatably supporting said carrier, feed means on said carrier, and within said casing for feeding an electrode through said carrier, a cam fixed on said carrier claim 14, comprising driving means supported by 10 said casing for driving said driven member, said casing comprising a pair of sections, means removably securing said sections together, one of said sections supporting said bearing and said driving means, and means for supporting the 15 other of said sections.

GEORGE J. ANDERSON. 

